Driving device for driving drill pipes and method for operating such a driving device

ABSTRACT

The invention relates to a so-called topdrive ( 16 ) in the form of a device to drive drill pipes and to a method for operating this drive, in which means are provided to heat the gearbox oil ( 46 ) used by the topdrive ( 16 ), which means can also be supplied by an emergency power unit and comprise a hydraulic unit ( 28 ) and a pressure limiting valve ( 40 ) of the topdrive ( 16 ), wherein hydraulic fluid ( 36 ) is circulated through the pressure limiting valve ( 40 ) to heat the gearbox oil ( 46 ) by the hydraulic unit ( 28 ), and the heat energy thus generated is transferred through a heat exchanger ( 48 ) through which the hydraulic fluid ( 36 ) flows to the gearbox oil ( 46 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The following invention relates to a drive device, hereafter identifiedin abbreviated form in accordance with standard technical terminology asa topdrive, for driving drill pipes for drilling boreholes inhydrocarbon deposits, e.g., petroleum or natural gas, or for exploitinggeothermal energy.

2. Description of the Related Art

Topdrives of this type are well known per se and comprise a gearbox bywhich the torque of a drive motor, also included in the topdrive, istransferred to the drill pipes.

One aspect of the gearbox for topdrives that is well known is the factthat this drive must only be operated above a minimum temperature whichis determined in particular by the type of gearbox oil. This minimumtemperature is in the range, for example, of minus 20° C. Whentemperatures are below this minimum temperature the gearbox must firstbe warmed up until it reaches a specified minimum operating temperature.This minimum operating temperature, for example, is in the range ofminus 15° C. A cold start procedure is provided to warm up the gearboxin this way.

The cold start procedure used up until now assumes that a stable linevoltage of 600/690 V is available at the main motor (drive motor) and ata frequency inverter supplying the main motor.

This type of line voltage and, in particular, stable line voltage is notalways available at locations where drilling rigs—and along with thesethe topdrives included therein—are operated. It would, therefore, bemore advantageous if the above-described cold start procedure werepossible using a voltage—for example, 442 V—available from an emergencypower unit. Precisely because of the above-described problems relatingto inconsistent line voltages, these emergency power units are typicallyavailable at the installation site of a drilling rig, and based on thetypical application situation for these emergency power units these arenormally also ready for use whenever a stable line voltage is notavailable.

Electrically operated heating, whether supplied from the grid or by anemergency power unit, to reliably provide the minimum operatingtemperature for the gearbox oil can generally be ruled out due to thelatent risk of explosion when operating the rig and the so-called ATEXdirectives that must be complied with here. The minimum approach herewould be to provide an extra fill level monitor for the gearbox oil sothat this in principle possible electrical heating is not turned on ordoes not stay on if the electrically heated heating element—for examplein the simplest case a resistance wire—is exposed and thus no heat istransferred to the gearbox oil, but instead the heating element islikely to burn out. Regardless of this factor, a possibleelectrically-operated heating with the necessary heating performancerequires a substantial amount of space. This space is not available oris typically occupied by other systems in the topdrive which alternatelymoves up and down within the drilling mast during the drillingoperation.

SUMMARY OF THE INVENTION

One object of the invention is therefore to propose a drive device ofthe type referenced above, that is, a topdrive in which it is possibleto heat the gearbox oil by another approach. Another object of theinvention is to provide a method for operating this type of topdrive.

This object is achieved according to the invention by the features ofthe independent claims.

In terms of the topdrive, that is, a drive device to drive drill pipeswhen drilling boreholes in hydrocarbon deposits in the form of atopdrive, the following is provided: In the well-known approach thetopdrive comprises a hydraulic unit including a pan for hydraulic fluid,in particular, hydraulic oil, in which pan hydraulic fluid is present ina topdrive that is ready to operate or is already operating. Thetopdrive furthermore by the known approach comprises a gearbox with agearbox oil pan in which gearbox oil is located in a topdrive that isready to operate or is already operating. A gearbox oil temperaturevalue for the temperature of the gearbox oil in the gearbox oil pan canbe measured by a temperature sensor identified with specific referenceas a gearbox oil temperature sensor.

The hydraulic fluid can be circulated by the hydraulic unit through apressure limiting valve included in the topdrive as a function of thegearbox oil temperature value.

Thus, if the gearbox oil temperature value is below a specified orspecifiable limit, i.e., a corresponding processing and logicaloperation linking the gearbox oil temperature value and the limiteffected by a circuit or software is provided for this purpose and isautomatically able to detect that a cold start procedure must beinitiated before the topdrive is put into operation. The cold startprocedure that can also be initiated automatically by detecting thissituation, that is, as a function of the gearbox oil temperature value,consists of having the hydraulic fluid circulated by the hydraulic unitthrough the pressure limiting valve. The thermal dissipation lossgenerated by the flow passing through the pressure limiting valveresults in the hydraulic fluid being heated. The hydraulic fluid thusheated can be passed by the hydraulic unit through a heat exchangerinstalled in the gearbox oil pan as a function of temperature and/ortime.

As a result, the heat generated at the pressure limiting valve by thehydraulic fluid is transferred through the heat exchanger installed inthe gearbox oil pan to the gearbox oil. This allows the gearbox oil tobe heated by the hydraulic fluid. This is sometimes also identifiedbelow as hydraulic gearbox oil heating. This approach can be transferredin an analogous or similar fashion to other units of a drilling rig.

Introduction of the heated hydraulic fluid into the heat exchanger canbe effected as a function of temperature and/or time. When the heatedhydraulic fluid is introduced into the heat exchanger as a function oftemperature, this introduction can be effected whenever the hydraulicfluid has reached a specified temperature. When the heated hydraulicfluid is introduced into the heat exchanger as a function of time, thisintroduction can be effected whenever the circulation of the hydraulicfluid through the pressure limiting valve has been effected at least fora specified or specifiable period of time and it can be assumed that thehydraulic fluid has undergone a rise in temperature necessary to heatthe gearbox oil.

In terms of a method of operating this topdrive or a topdrive that isdescribed below in more detail, a provision is made whereby thehydraulic unit is activated automatically as a function of the gearboxoil temperature value to circulate the hydraulic fluid through thepressure limiting valve and whereby the hydraulic fluid is passedautomatically as a function of temperature and/or time through a heatexchanger installed in the gearbox oil pan.

The above-referenced object of the invention is also achieved by acontrol device to control the operating method of the topdrive thatperforms the cold start procedure, which device functions according tothe method described here and below, and for this purpose comprisesmeans to implement the method. The invention is preferably implementedin software; it can just as well, however, be implemented in hardware,or in both software and hardware. The invention is thus also a computerprogram comprising program code instructions that can be executed by acomputer, but is also a storage medium comprising this computerprogram—in other words a computer program product comprising programcoding means, and finally also a control device, in the storage mediumof which this computer program is loaded or can be loaded as means toimplement the method.

Whenever reference is made here or below to the fact that a specificaction is effected automatically, this must be understood to mean thatthe action is performed or initiated by the control device or at leastunder the control of the control device. Examples of such actions arecomparing the gearbox oil temperature value with the limit for thegearbox oil temperature, and activating the hydraulic unit to circulatethe hydraulic fluid through the pressure limiting valve as a function ofthe gearbox oil temperature value.

The advantage of the invention is the fact that components and units areused to heat the gearbox oil that are already included in thetopdrive—specifically, the hydraulic unit and the pressure limitingvalve. Another advantage is the fact that the action of heating thegearbox oil proposed here only requires the operation of the hydraulicunit. The hydraulic unit can be very easily operated by an emergencypower unit. Heating the gearbox oil as proposed here is thus independentof any line voltage which is sometimes not available or is not availableat a sufficient level of stability. Since components and units are beingused to heat the gearbox oil that are already in any case included inthe topdrive, no additional installation space is required in the regionof the topdrive. The (additionally required) heat exchanger is locatedwithin the volumetric space of the gearbox oil pan, the geometry andouter dimensions of which do not require any modification, with theresult that the heat exchanger located in the gearbox oil pan also doesnot require any additional installation space.

Advantageous embodiments of the invention are described in the dependentclaims. References used here relate to the further development of theobject of the main claim by means of the features of the specificdependent claim; they must not be understood to imply abandonment ofobtaining independent, subject-matter-specific protection for thecombination of features of the referenced dependent claims. Furthermorein terms of interpreting the claims relating to a more detaileddescription of a feature in a subordinate claim, it must be assumed thatthis restriction is not present in the respective preceding claims.

Since the various subject matter of the dependent claims can constituteseparate and independent inventions in terms of the prior art on thepriority date, the applicant reserves the right to make them the subjectmatter of independent claims or declarations of division. They canfurthermore also contain independent inventions that comprise anembodiment which is independent of the various subject matter of thepreceding claims.

In one embodiment of the drive device (the topdrive), this device ordrive comprises a temperature sensor that is identified for purposes ofdifferentiation as a hydraulic fluid temperature sensor. This hydraulicfluid temperature sensor enables a hydraulic fluid temperature value tobe measured for a hydraulic fluid temperature in the pan of thehydraulic unit. The hydraulic fluid can then be passed by the hydraulicunit through the heat exchanger that is installed in the gearbox oil panas determined by this hydraulic fluid temperature value.

An automatic and temperature-dependent introduction of the hydraulicfluid into the heat exchanger is thus possible based on the hydraulicfluid temperature value obtained by the hydraulic fluid temperaturesensor. In terms of introducing the hydraulic fluid into the heatexchanger, the point of reaching a threshold value is monitored relativeto the hydraulic fluid temperature value. Sufficient heating of thehydraulic fluid is recognized as soon as this threshold value has beenreached. The heated hydraulic fluid can now be passed to the heatexchanger, thereby allowing heat to be transferred there to the gearboxoil surrounding the heat exchanger.

In another or alternative embodiment of the drive device (the topdrive),a directional control valve is disposed between the hydraulic unit andthe heat exchanger in the flow direction of the hydraulic fluid. Thedirectional control valve enables the hydraulic fluid to beautomatically passed either to the pressure limiting valve or to theheat exchanger. It is possible to divert or divide the hydraulic fluidflow depending on the location of the directional control valve(upstream from the directional control valve or downstream from thedirectional control valve).

If the directional control valve is located upstream from the pressurelimiting valve, the directional control valve can be used to pass thehydraulic fluid either exclusively through the pressure limiting valveor exclusively through the heat exchanger. A first hydraulic branchincluding the pressure limiting valve and a second hydraulic branchincluding the heat exchanger respectively connect to the heat exchanger.The first hydraulic branch or the second hydraulic branch is activedepending on the position of the directional control valve.

If the directional control valve is located downstream from the pressurelimiting valve, only the hydraulic branch through the pressure limitingvalve is active when the directional control valve is closed. If thedirectional control valve is open, the hydraulic branch through thepressure limiting valve remains unaffected by this and continues to beactive. The flow of hydraulic fluid divides, part of it following thefirst hydraulic branch through the pressure limiting valve and part ofit following the second hydraulic branch with the open directionalcontrol valve and the heat exchanger that is connected thereto.

This type of directional control valve is thus both an efficient andsimultaneously simple means of implementing a first hydraulic cycle inwhich a thermal dissipation loss can be generated by the pressurelimiting valve located there, thereby heating the hydraulic fluid andsimultaneously implementing a second hydraulic cycle in which asufficiently heated hydraulic fluid can be passed to a heat exchanger inthe gearbox oil pan in order to heat the gearbox oil there.

In one embodiment of the drive device (topdrive), in particular, whichallows the volumetric flow generated by the hydraulic unit to be dividedbased on the location of the directional control valve, a flow controlvalve (throttle valve) is disposed in the flow direction of thehydraulic fluid between the hydraulic unit and the heat exchanger. Thevolumetric flow to the heat exchanger that is provided by the hydraulicunit can be adjusted by the flow control valve. As the flow controlvalve is opened further, thus producing less resistance for thehydraulic fluid flowing through the flow control valve, more and morehydraulic fluid flows along the path with the flow control valve.Conversely, that much less hydraulic fluid flows along the path with theflow control valve as the flow control valve is closed further. Morehydraulic fluid then flows along the path with the pressure limitingvalve included in the hydraulic unit since the volumetric flow isdivided. The flow control valve thus enables adjustments to be made asto the level at which the hydraulic fluid should continue to generateheat by further circulating the hydraulic fluid, and as to the level atwhich heating of the gearbox oil should be effected by introducing thehydraulic fluid into the heat exchanger.

What is also found with the flow through the flow control valve—just aswas described above for the pressure limiting valve—is that a thermaldissipation loss is generated so as to produce heating of the hydraulicfluid flowing through the flow control valve. The heat thus generated isalso passed to the heat exchanger where it is also effective in heatingthe gearbox oil.

In an optional approach, another pressure limiting valve can be providedin the flow direction of the hydraulic fluid between the hydraulic unitand the heat exchanger. This limits the effective pressure of thehydraulic fluid to the extent that the fluid can be passed without anyrisk to the heat exchanger.

One particularly capable form that has been found for the heat exchangeris a so-called finned tube since, as is well known, this tube has aneven significantly greater surface area when compared with a tube rolledup in the shape of a coil and through which the hydraulic fluid flows,and thereby ensures an especially effective transfer of heat to thegearbox oil surrounding the heat exchanger/finned tube.

In one embodiment of the method referenced above for operating the drivedevice/topdrive, provision is made in this drive device that includes agearbox oil temperature sensor to detect the gearbox oil temperature ofthe gearbox oil in the gearbox oil pan whereby the hydraulic unit isautomatically activated to circulate the hydraulic fluid through thepressure limiting valve at a gearbox oil temperature value below aspecified or specifiable temperature limit (for example, minus 20° C.).Circulation of the hydraulic fluid and thus heating of the hydraulicfluid are effected automatically, but also only as required based onthis monitoring of the gearbox oil temperature value. When gearbox oiltemperature value detected as the parameter for the gearbox oiltemperature is below the temperature limit, a situation is recognizedwhich requires a cold start procedure before starting up the topdrive.Recognizing the requirement for this cold start procedure and initiatingthis cold start procedure by circulating the hydraulic fluid through thepressure limiting valve can be effected automatically by implementingappropriate processing and logical operation linking the gearbox oiltemperature value and the temperature limit by means of a dedicatedcircuit or software. As a result, automatic circulation of the hydraulicfluid through the pressure limiting valve is effected as a function ofthe gearbox oil temperature value.

In one embodiment of the method referenced above for operating the drivedevice/topdrive or embodiments thereof, A provision is made in thisdrive device, which additionally includes a hydraulic fluid temperaturesensor to detect a hydraulic fluid temperature value for a temperatureof the hydraulic fluid in the pan of the hydraulic unit, whereby thehydraulic fluid is passed automatically through the heat exchangerinstalled in the gearbox oil pan based on a hydraulic fluid temperaturevalue above a specified or specifiable temperature threshold value.Detection of the temperature of the hydraulic fluid in the form of ahydraulic fluid temperature value and the comparison thereof with atemperature threshold value is an efficient and simple means ofperforming an automatic and temperature-dependent introduction ofhydraulic fluid into the heat exchanger that is installed in the gearboxoil pan. One possible temperature for the temperature threshold value,for example, is a temperature of +40° C. Sufficient heating of thehydraulic fluid is detected when the hydraulic fluid temperature valuereaches this temperature or the relevant temperature threshold value.The heat energy absorbed from the hydraulic fluid can be transferred tothe gearbox oil in order to heat it. To this end the hydraulic fluidflow is passed to the heat exchanger or at least also to the heatexchanger, and for this purpose a path is enabled for the hydraulicfluid to move from the hydraulic unit to the heat exchanger.

In another embodiment of the method referenced above for operating thedrive device/topdrive or embodiments thereof, provision is made in thisdrive device, which includes a directional control valve disposedupstream from the pressure limiting valve between the hydraulic unit andthe heat exchanger, whereby the hydraulic fluid flow is switched betweena first path through the pressure limiting valve and a second paththrough the heat exchanger by automatically activating the directionalcontrol valve. The directional control valve and the appropriateactivation thereof is a simple and efficient means of opening a path forthe hydraulic fluid from the hydraulic unit to the heat exchanger. Thedirectional control valve passes the hydraulic fluid flow exclusivelyeither through the pressure limiting valve (to heat the hydraulic fluid)or to the heat exchanger (to transfer heat to the gearbox oil).

In an alternative embodiment of the method referenced above foroperating the drive device/topdrive or embodiments thereof, provision ismade in this drive device, which unlike the above-described deviceincludes a directional control valve between the hydraulic unit and theheat exchanger downstream from the pressure limiting valve instead ofupstream from the pressure limiting valve, whereby the hydraulic fluidflow is switched by automatically activating the directional controlvalve between a first path through the pressure limiting valve and asecond path that at least also includes the heat exchanger. Thedirectional control valve and the appropriate activation thereof is inthis embodiment thus also a simple and efficient means of opening a pathfor the hydraulic fluid from the hydraulic unit to the heat exchanger.Unlike the above-described embodiment, the first path for the hydraulicfluid through the pressure limiting valve is always open when thedirectional control valve is located downstream from the pressurelimiting valve. Activating the directional control valve to open thepath for the hydraulic fluid through the heat exchanger thus results inthe hydraulic fluid flow being divided between the first path (throughthe pressure limiting valve) and the second path (through the heatexchanger). The advantage here is that the hydraulic fluid flowing alongthe first path continues to be heated as is the case with the exclusivecirculation through the pressure limiting valve, with the result thatthe heat continuing to be absorbed from the hydraulic fluid is availablecontinuously for transfer to the gearbox oil.

The advantage of the invention and embodiments thereof also entailsspecifically the fact that there is a reliable expectation of producinga transferable heat output of 2 kW to 3 kW due to the heating of thehydraulic fluid and the circulation thereof through the pressurelimiting valve. As a result, the gearbox oil of a topdrive that isoffered by the applicant and identified as TD-500-HT can be heated from−40° C. to approximately −15° C. within about an hour. This heating ofthe gearbox oil as part of a cold start procedure—or maintenance ofgearbox oil heat—is only possible by means of the auxiliary drives thatcan be readily supplied with power by an emergency power unit,specifically here the hydraulic unit. The heating or maintenance ofgearbox oil heat are provided here by a “hydraulic gearbox oil heating”that essentially eliminates the need for additional functional unitsassociated with the topdrive, specifically since the hydraulic unit andthe pressure limiting valve by means of which the hydraulic fluid iscirculated for heating purposes are already included in the topdrive.Other means instead of a temperature sensor (gearbox oil temperaturesensor, hydraulic fluid temperature sensor) are possible fordetermining/detecting/calculating/estimating a temperature value—forexample, a mathematical model that enables the relevant temperaturevalue to be determined/calculated/and/or estimated based on otherparameters, in particular, parameters detected at the topdrive, forexample, based on an ambient temperature and a period of operation. Whatthen replaces the gearbox oil temperature sensor and/or hydraulic fluidtemperature sensor is an appropriate means ofdetermining/detecting/calculating/estimating—collectively referenced as“determining” without abandoning the wider general applicability ofmeaning—the gearbox oil temperature or the hydraulic fluid temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

The following discussion describes an exemplary embodiment of theinvention in more detail based on the drawing. Corresponding items orelements in all figures are provided with identical reference numerals,although not all reference numerals are marked in all figures in orderto maintain clarity.

The exemplary embodiment or each exemplary embodiment must not beunderstood as implying a restriction of the invention. On the contrary,numerous alterations and modifications are possible within the scope ofthe invention, in particular, those variants and combinations which canbe derived by a person skilled in the art by, for example, combining ormodifying individual features or elements or procedural steps that aredescribed in general or in the specification and are contained in theclaims and/or the drawing, with the aim of achieving the object of theinvention, and which variants or combinations through combinablefeatures result in a new inventive subject matter or in new proceduralsteps or procedural step sequences, including to the extent these relateto working methods.

FIG. 1 depicts a section of a drilling rig comprising a mast and aso-called topdrive of the type known per se which can move therein, suchas that for employing a device for manipulating drill pipe elements;

FIG. 2 is a view of a topdrive including additional details,specifically a hydraulic unit and a gearbox housing;

FIG. 3 is a hydraulic diagram comprising a first and a second hydrauliccycle for hydraulic fluid conveyed by the hydraulic unit;

FIG. 4 is an enlarged view of the gearbox housing of the topdrive inFIG. 2, comprising a heat exchanger that is installed therein andfunctions to transfer heat to gearbox oil located in the gearboxhousing, which heat exchanger in turn has hydraulic fluid flowingthrough it that has been heated by the hydraulic unit; and

FIG. 5 is the hydraulic diagram of FIG. 3 together with a control devicethat is provided and intended to receive measurement data from and sendcontrol signals to individual units included in the hydraulic diagram.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

The diagram in FIG. 1 depicts as part of a drilling rig a mast 10including a possible embodiment of an associated substructure 12. Aso-called monkey board 14 is located here on mast 10, which monkey boardis provided in the manner known per se for the upright, that is,vertical mounting of drill pipe elements. A so-called topdrive 16 isinstalled in the manner known per se in mast 10, which topdrive isprovided during operation to lower and lift the drill pipes (not shown;indicated only by broken lines) and to rotate the drill pipes so as toperform the drilling operation. Topdrive 16 is thus a drive device todrive drill pipes when drilling boreholes in hydrocarbon deposits or forexploiting geothermal energy. The term topdrive is a typically usedtechnical term identifying this type of drive device. This term is usedaccordingly here and below. The term topdrive is used here specificallyalso as the abbreviated form for the otherwise possible designation ofthis type of drive device in the form of drive device to drive drillpipes when drilling boreholes in hydrocarbon deposits or for theexploitation of geothermal energy.

Topdrive 16 is suspended in mast 10 on a roller block 18. Roller block18 and a crown block 20 located in the area of a mast crown 20 functiontogether like a pulley block. A cable (not shown) runs from crown block20 for vertical movement of topdrive 16 to a lifting apparatus providedin the area of the drill rig. Topdrive 16 is held in mast 10 by guiderails 22 for vertical movement that can be actuated by the liftingapparatus.

The diagram in FIG. 2 reveals an embodiment of a topdrive 16 includingadditional details. In terms of a description of specific details of thetopdrive, reference is made, for example, to DE 10 2009 039 022 A1. Thedetails that are significant for the following description of topdrive16 are: a drive unit 24 in the form of an electric motor, a gearboxhousing 26 including a gearbox (not shown) located therein thatappropriately changes the rotational speed and the torque of drive unit24 so that the drill pipes can be driven appropriately during thedrilling action, and a hydraulic unit 28 that, for example, supplies theoperating pressure to hydraulically move so-called drill pipe bails 30.An oil sump 32 is created inside a bottom section of gearbox housing 26.This is where portions of the gearbox oil used for the gearbox arelocated.

The illustration in FIG. 3 is a schematic simplified view of theabove-mentioned details of topdrive 16 (FIG. 2) in the form of ahydraulic diagram. The lower section of the diagram shows hydraulic unit28. A pan 34 for hydraulic fluid 36 is included in hydraulic unit 28,hydraulic fluid being located in the pan of topdrive 16 when the driveis ready to operate or in operation. In addition, hydraulic unit 28furthermore includes a hydraulic pump 38 provided to convey hydraulicfluid 36 together with a motor to operate the pump, a pressure limitingvalve 40, and a temperature sensor 42. Temperature sensor 42 measures atemperature of hydraulic fluid 36 (hydraulic fluid temperature). Thistemperature sensor is thus also identified as hydraulic fluidtemperature sensor 42. Hydraulic fluid temperature sensor 42 supplies ahydraulic fluid temperature value T1 as the hydraulic fluid temperatureor as a parameter for the hydraulic fluid temperature.

The hydraulic diagram of FIG. 3 in the region of hydraulic unit 28illustrates how hydraulic fluid 36 can be circulated through pressurelimiting valve 40 by hydraulic unit 28—specifically by hydraulic pump 38included therein. Hydraulic fluid 36 is conveyed from pan 34 and thendischarged from the outlet of pressure limiting valve 40 into pan 34.This creates a circuit for hydraulic fluid 36. This circuit isidentified as the first circuit, or in abbreviated form as the firstcycle, to differentiate it from another circuit that is described below.

When hydraulic fluid 36 is circulated in the first cycle throughpressure limiting valve 40, heating of hydraulic fluid 36 is effected(hydraulic heating) by means of the thermal dissipation loss generatedin pressure limiting valve 40. Pressure limiting valve 40 is part ofhydraulic unit 28. Hydraulic unit 28 in turn is part of topdrive 16.This justifies the designation of pressure limiting valve 40 andhydraulic unit 28 as parts of topdrive 16, that is, as being comprisedby topdrive 16.

The top area of the diagram in FIG. 3 shows a gearbox oil pan 44 locatedin gearbox oil housing 26 of topdrive 16. When topdrive 16 is operating,gearbox oil 46 is located in gearbox oil pan 44, the oil—just as forhydraulic fluid 36—is shown only by the surface of a fluid levelprovided as an example. Heat exchanger 48 is located in a lower sectionof gearbox oil pan 44, that is, at the level of oil sump 32 (FIG. 2). Atemperature sensor 50 is furthermore located in gearbox housing 26.

This temperature sensor 50 measures a temperature of the gearbox oil(gearbox oil temperature) in the area of oil sump 32. For purposes ofdifferentiation this temperature sensor 50 is also identified as gearboxoil temperature sensor 50. Gearbox oil temperature sensor 50 supplies agearbox oil temperature value T2 as a parameter for the gearbox oiltemperature.

Heat exchanger 48 is part of a second hydraulic cycle starting fromhydraulic unit 28, where the first hydraulic cycle—as described above—iscreated inside hydraulic unit 28 and is active when hydraulic fluid 36is circulated through pressure limiting valve 40. Included in secondhydraulic unit 28 are: a flow control valve 52, pressure limiting valve54, directional control valve 56, and another pressure limiting valve 58provided to protect heat exchanger 48.

The illustration of FIG. 4 shows partially cutaway gearbox housing 26,thereby providing a view of the interior thereof, and gearbox oil pan 44provided there together with oil sump 32 in a lower section of gearboxoil pan 44. Heat exchanger 48 is disposed in gearbox oil pan 44 in thearea of oil sump 32, the heat exchanger being shown in the form of twotubular coils. The two tubular coils are interconnected so that theabove-mentioned second hydraulic cycle comprises the two tubular coils.The coiled tubes or individual coiled tubes or more than two coiledtubes shown can be implemented as so-called finned tubes in order toenlarge the effective surface area.

When the second cycle is active, hydraulic fluid 36 conveyed byhydraulic unit 28 flows into heat exchanger 48 at in-flow side 60, thenleaves heat exchanger 48 and thus gearbox housing 26 on a return side62.

The illustration in FIG. 5 is a partial repeat of the illustration inFIG. 3. Not all of the reference numerals are repeated so as not todiminish the clarity of FIG. 5. For this reason reference is made to theillustration of FIG. 3. FIG. 5 otherwise is a schematically simplifiedcontrol device 64 as an example of means to implement the methoddescribed here and below. Control device 64 comprises, for example, inan approach known per se a processing unit, not shown, in the form of oranalogous to a microprocessor and a storage medium, also not shown, thatcan be loaded with a control program that is executed when controldevice 64 is operating by the processing unit thereof

The functionality implemented in the control program and the definedfunctionality of control device 64, which can alternatively also berealized by conventional means, that is, in hardware, is summarized asfollows:

Control device 64 measures at least gearbox oil temperature value T2supplied by gearbox oil temperature sensor 50. Hydraulic unit 28 isactivated to circulate hydraulic fluid 36 through pressure limitingvalve 40 as a function of gearbox oil temperature value T2. The gearboxoil temperature correlation can be implemented here by comparing gearboxoil temperature value T2 with a specified or specifiable temperaturelimit, and by activating hydraulic unit 28 to circulate hydraulic fluid36 through pressure limiting valve 40 whenever gearbox oil temperaturevalue T2 is below the temperature limit. The temperature limit can beimplemented as the content of a memory location of control device 64.The temperature limit can thus be specified but at the same time can beadapted to the specific conditions, that is, for example, to the gearboxoil and the viscosity thereof One possible example of a temperaturelimit is minus 20° C.

In addition, control device 64 functions to have hydraulic fluid 36passed through heat exchanger 48 installed in gearbox oil pan 44 as afunction of temperature and/or time. To this end directional controlvalve 56 is activated which in the configuration shown in FIG. 3 andFIG. 5 in the open state opens the cycle and thus the path for hydraulicfluid 36 into heat exchanger 48, while the first cycle through pressurelimiting valve 40 remains active. Flow control valve 52 functions hereto divide the volumetric flow of hydraulic fluid 36 between the firstand the second cycle.

The above-described detection of measured values by control device 64and the activation of individual units effected by control device 64 areillustrated by arrows in the diagram of FIG. 5. The paths of action thusshown are implemented in practice as wire connections through which themeasured values can be received and control signals can be sent.

If control device 64 effects a time-dependent introduction of hydraulicfluid 36 into heat exchanger 48, control device 64 includes a timer thatis started with the start of circulation of hydraulic fluid 36 throughpressure limiting valve 40, and during the sequence generates a signal,on the basis of which control device 64 generates the signal to activatedirectional control valve 65 to open the second cycle for hydraulicfluid 36. The timer can be implemented by the well-known approach as adecrementing or incrementing counter. The start and the target value ofthis counter can be specified as content of a memory location of controldevice 64. The relevant value used is thus an empirical value that canbe adapted to the specific conditions. Provision can be made in oneparticular embodiment whereby control device 64 manages a plurality ofthese values from which a user selects a value appropriate to the givensituation based on hydraulic fluid 36 is used, the delivery volume ofhydraulic unit 28, that is, for example, twenty liters per minute, andthe pressure at which pressure limiting valve 40 limits/reduces thepressure of hydraulic fluid 36, in other words, for example, 210 bar.The values managed by control device 64 can then, for example, beorganized in a multi-dimensional matrix, and an appropriate time valueis selected from a specified value or selection of individualparameters. This approach achieves the goal of eliminating the need tomeasure the hydraulic fluid temperature, and hydraulic fluid temperaturesensor 42 that is otherwise provided to measure the hydraulic fluidtemperature can accordingly be eliminated.

If hydraulic fluid temperature sensor 42 is present and is used, thetemperature-dependent and/or time-dependent introduction of hydraulicfluid 36 into heat exchanger 48 is effected as a function of temperatureor at least also as a function of temperature. To this end, controldevice 64 measures hydraulic fluid temperature value T1 supplied byhydraulic fluid temperature sensor 42 at least when hydraulic fluid 36is circulated through pressure limiting valve 40, then compares thisvalue with a specified or specifiable temperature threshold value. Thetemperature threshold value is implemented, in particular, as content ofa memory location of control device 64. The temperature threshold valueis thus specifiable, but can also be adapted to relevant conditions,such as, for example, the volumetric conditions of hydraulic fluid 36and gearbox oil 46, and/or as a parameter for the transfer of heat atheat exchanger 48 to gearbox oil 46. One possible threshold value, forexample, is a value of +40° C. Whenever hydraulic fluid temperaturevalue T1 reaches or exceeds the relevant temperature threshold value,hydraulic fluid 36 that is then sufficiently heated is passed throughheat exchanger 48 installed in gearbox oil pan 44. To this end controldevice 64 activates directional control valve 56, as described above.

This type of hydraulic gearbox oil heating remains active until at leastone specified minimum operating temperature has been reached for gearboxoil 46. To accomplish this control device 64 monitors gearbox oiltemperature value T2 continuously or at regular intervals following theinitial activation of circulating hydraulic fluid 36 through pressurelimiting valve 40. Once gearbox oil temperature value T2 has reached orexceeded the specified minimum operating temperature of gearbox oil 46,the hydraulic gearbox oil heating can be deactivated. The hydraulicgearbox oil heating again becomes active automatically under the controlof control device 64 if gearbox oil temperature value T2 falls below thespecified minimum operating temperature, or the at the latest whenevergearbox oil temperature value T2 falls below the minimum temperature.

The hydraulic gearbox oil heating, that is, the method for the operatingtopdrive 16 described here can be started automatically whereby controldevice 64 continuously monitors gearbox oil temperature value T2 and thehydraulic gearbox oil heating is activated if the minimum operatingtemperature or the minimum temperature at least falls below a givenlevel. Activation of the hydraulic gearbox oil heating can also beeffected by an approach wherein gearbox oil temperature value T2 isevaluated as described above in connection with a manual or automaticactivation of topdrive 16, and the hydraulic gearbox oil heating isactivated as necessary. Activation of topdrive 16 is then delayed orprevented by control device 64 until at least the minimum operatingtemperature has been reached.

Heating of gearbox oil 46 can also be effected using other heat sourcesindependently of the above-described hydraulic gearbox oil heating.Gearbox oil 46 and/or hydraulic fluid 36 can then function as aheat-sink for heat generated at other locations. A switchable heatexchanger or separate heat exchanger (not shown) can be provided forthis purpose in gearbox oil pan 44 and/or pan 34 for hydraulic fluid 36,hot steam being introduced, for example, to dissipate heat from anexternal heat source.

Individual key aspects of the description submitted here can besummarized as follows: So-called topdrive 16 is described in the form ofa device to drive drill pipes, and a method is described to operate thedrive in which means are provided to heat gearbox oil 46 used bytopdrive 16, which means can be supplied by an emergency power unit, andcomprise hydraulic unit 28 and pressure limiting valve 40 of topdrive16, wherein hydraulic fluid 36 is circulated by hydraulic unit 28through pressure limiting valve 40 to heat gearbox oil 46, and the heatenergy thus generated is transferred to gearbox oil 46 through heatexchanger 48 through which hydraulic fluid 36 flows.

REFERENCE LIST

-   10 mast (drilling mast)-   12 substructure-   14 monkey board-   16 topdrive-   18 roller block-   20 crown block-   22 guide rail-   24 drive unit (in the topdrive)-   26 gearbox housing (in the topdrive)-   28 hydraulic unit (in the topdrive)-   30 drill pipe bail (on the topdrive)-   32 oil sump (in the gearbox housing)-   34 pan (for the hydraulic fluid)-   36 hydraulic fluid-   38 hydraulic pump (in the hydraulic unit)-   40 pressure limiting valve-   42 temperature sensor/hydraulic fluid temperature sensor-   44 gearbox oil pan-   46 gearbox oil-   48 heat exchanger-   50 temperature sensor/gearbox oil temperature sensor-   52 flow control valve-   54 pressure limiting valve-   56 directional control valve-   58 additional pressure limiting valve-   60 in-flow side (of the heat exchanger)-   62 return flow side (of the heat exchanger)-   64 control device-   T1 hydraulic fluid temperature value-   T2 gearbox oil temperature value

1. Drive device for driving drill pipes when drilling boreholes inhydrocarbon deposits in the form of a topdrive (16), wherein thetopdrive (16) comprises: a hydraulic unit (28) including a pan (34) forhydraulic fluid (36) in which hydraulic fluid (36) is located in anoperationally ready topdrive (16), and a gearbox including a gearbox oilpan (44) in which gearbox oil (46) is located in an operationally readytopdrive (16), wherein a gearbox oil temperature value (T2) for thetemperature of the gearbox oil (46) in the gearbox oil pan (44) can bemeasured by a gearbox oil sensor (50), wherein the hydraulic fluid (36)can be circulated by the hydraulic unit (28) through a pressure limitingvalve (40) included in the topdrive (16) as a function of the gearboxoil temperature value (T2), and wherein the hydraulic fluid (36) can bepassed by the hydraulic unit (28) through a heat exchanger (48)installed in the gearbox oil pan (44) as a function of temperatureand/or time.
 2. Drive device according to claim 1, wherein the topdrive(16) further comprises a hydraulic fluid temperature sensor (42) tomeasure a hydraulic fluid temperature value (T1) for a temperature ofthe hydraulic fluid (36) in the pan (34) of the hydraulic unit (28), andwherein the hydraulic fluid (36) can be passed through the heatexchanger (48) installed in the gearbox oil pan (44) as a function ofthe hydraulic fluid temperature value (T1) by means of the hydraulicunit (28).
 3. Drive device according to claim 1, wherein a flow controlvalve (52) is disposed between the hydraulic unit (28) and the heatexchanger (48).
 4. Drive device according to claim 1, wherein adirectional control valve (56) is disposed between the hydraulic unit(28) and the heat exchanger (48).
 5. Drive device according to claim 1,comprising a heat exchanger (48) in the form of a finned tube.
 6. Methodfor operating a drive device designed to drive drill pipes for drillingboreholes in hydrocarbon deposits, the drive device being in the form ofa topdrive (16) according to claim 1, wherein the hydraulic unit (28) isactivated to circulate the hydraulic fluid (36) through the pressurelimiting valve (40) as a function of the gearbox oil temperature value(T2), and wherein the hydraulic fluid (36) is passed through a heatexchanger (48) installed in the gearbox oil pan (44) as a function oftemperature and/or time.
 7. Method according to claim 6, wherein thehydraulic unit (28) is activated to circulate the hydraulic fluid (36)through the pressure limiting valve (40) when a gearbox oil temperaturevalue (T2) is below a specified or specifiable temperature limit. 8.Method according to claim 6, wherein the to drive further comprises ahydraulic fluid temperature sensor (42) to measure a hydraulic fluidtemperature value (T1) for a temperature of the hydraulic fluid (36) inthe pan (34) of the hydraulic unit (28), and wherein the hydraulic fluid(36) is passed through the heat exchanger (48) installed in the gearboxoil pan (44) when the hydraulic fluid temperature value (T1) is above aspecified or specifiable temperature threshold.
 9. Method according toclaim 6, or 8 for wherein the topdrive (16) further comprises adirectional control valve (56) disposed between the hydraulic unit (28)and the heat exchanger (48) upstream from the pressure limiting valve(40), and wherein the hydraulic fluid flow is switched between a firstpath through the pressure limiting valve (40) and a second path throughthe heat exchanger (48) by automatically activating the directionalcontrol valve (56).
 10. Method according to claim 6, wherein thetopdrive (16) further comprises a directional control valve (56)disposed between the hydraulic unit (28) and the heat exchanger (48)downstream from the pressure limiting valve (40), and wherein thehydraulic fluid flow is switched between a first path through thepressure limiting valve (40) and a second path through the pressurelimiting valve (40) as well as through the heat exchanger (48) byautomatically activating the directional control valve (56).
 11. Methodaccording to claim 7, wherein the topdrive (16) further comprises ahydraulic fluid temperature sensor (42) to measure a hydraulic fluidtemperature value (T1) for a temperature of the hydraulic fluid (36) inthe pan (34) of the hydraulic unit (28), and wherein the hydraulic fluid(36) is passed through the heat exchanger (48) installed in the gearboxoil pan (44) when the hydraulic fluid temperature value (T1) is above aspecified or specifiable temperature threshold.
 12. Drive deviceaccording to claim 2, wherein a flow control valve (52) is disposedbetween the hydraulic unit (28) and the heat exchanger (48).
 13. Drivedevice according to claim 1, wherein a directional control valve (56) isdisposed between the hydraulic unit (28) and the heat exchanger (48)upstream from the pressure limiting valve (40).
 14. Drive deviceaccording to claim 1, wherein a directional control valve (56) isdisposed between the hydraulic unit (28) and the heat exchanger (48)downstream from the pressure limiting valve (40).